Pregnancy Week by Week
Pregnancy Week by Week Guide (Weeks 4-40)
Shelbi Kohler, certified birth doula & mother of seven
Every week of pregnancy brings something new — a beating heart, tiny fingers, hiccups you can feel from the outside. Pick your week below and see what's happening with your baby, what your body is doing, and a little encouragement from someone who's been through it seven times.
Due Date Calculator
Enter either the first day of your last menstrual period (LMP), or a due date your provider has given you.
Explore your pregnancy
Slide through every week
Drag the slider to watch your baby grow from a poppy seed to a full newborn — 4 weeks to 40.
4 weeks
As small as a poppy seed
Your baby is still tiny — the embryo is now fully implanted in the uterus and the amniotic sac is beginning to form.
Your week-by-week timeline
All 37 weeks, organized by trimester
Tap any week to see how big your baby is, what's developing, what your body might be feeling, and a note from Shelbi.
First Trimester
Weeks 1-12The foundation — when your baby develops from a cluster of cells to a recognizable fetus with all major organs forming.
As small as a poppy seed
See week 4 →
As small as an apple seed
See week 5 →
As small as a lentil
See week 6 →
As small as a blueberry
See week 7 →
As small as a raspberry
See week 8 →
As small as a grape
See week 9 →
As small as a strawberry
See week 10 →
As small as a fig
See week 11 →
As small as a lime
See week 12 →Second Trimester
Weeks 13-26The growth phase — when your baby develops from a tiny fetus to a baby that could potentially survive outside the womb.
Growing fast
See week 13 →
Practicing first expressions
See week 14 →
Stretching out
See week 15 →
Getting coordinated
See week 16 →
Building fat stores
See week 17 →
Ears reach their final spot
See week 18 →
Cocooned in vernix
See week 19 →
Halfway there!
See week 20 →
A brain growth spurt
See week 21 →
Practice breaths begin
See week 22 →
Lungs gearing up
See week 23 →
Viability week
See week 24 →
Filling out
See week 25 →
Rehearsing sucking and swallowing
See week 26 →Third Trimester
Weeks 27-40The finishing touches — when your baby gains weight, matures lungs and brain, and gets ready to meet you.
Third trimester prep
See week 27 →
Stronger kicks and stretches
See week 28 →
Rapid weight gain begins
See week 29 → Running out of room
See week 30 →
Built, now getting stronger
See week 31 →
Breathing practice continues
See week 32 →
Up to half a pound a week
See week 33 →
Smoother skin, longer nails
See week 34 →
Settling head-down
See week 35 →
Counting down
See week 36 →
Early term
See week 37 →
Fine-tuning for birth
See week 38 →
Full term!
See week 39 →
Due date week
See week 40 →Common questions
Week-by-week basics
How many weeks is a full-term pregnancy? +
A full-term pregnancy lasts about 40 weeks from the first day of your last menstrual period. Babies born between 37 and 42 weeks are considered term, with 39–40 weeks being ideal for most births.
What weeks are in each trimester? +
The first trimester runs through week 12, the second trimester covers weeks 13 through 26, and the third trimester runs from week 27 until birth.
How do I calculate my due date? +
The most common method counts 280 days (40 weeks) from the first day of your last menstrual period. Use our free due date calculator above — enter your LMP or your provider's due date and see exactly where you are week by week.
Is it normal for symptoms to differ week to week? +
Absolutely. Every pregnancy is different, and even the same person can feel completely different from one week to the next. These guides describe what's typical, not what's required — always check in with your provider if something feels off.
Track every week in the free True Joy Birthing app
Weekly updates, your birth plan, and doula-backed guidance — all in one place, all free.
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